[builder] Rewrite replace paths to be absolute in generated go.mod

[milas]

Description

Convert all relative paths to be absolute for replace directives the same way that is done for modules/components.

This ensures that the output_path isn't tied to the location of the builder YAML config.

For example:

/
├── work
│   ├── mycollector
│   │   └── builder.yaml
│   ├── mylib
│   │   └── go.mod
└── dist
    └── my-collector

OCB YAML - /work/mycollector/builder.yaml

replaces:
 - registry.test/somemodule => ../mylib

Build

cd /work/mycollector
DIST_OUTPUT_PATH=/dist ocb --config ./builder.yaml

Before these changes

• Generated go.mod's replace would end up resolving to /mylib

After these changes

• Generated go.mod's replace resolves to /work/mylib

Link to tracking issue

n/a

Testing

Added unit test

Documentation

Copious comments in code, nothing user-facing

[codecov]

Codecov Report

Attention: Patch coverage is 58.53659% with 17 lines in your changes missing coverage. Please review.

Project coverage is 91.46%. Comparing base (eb00c82) to head (b75508d).
Report is 127 commits behind head on main.

Files with missing lines	Patch %	Lines
cmd/builder/internal/builder/config.go	58.53%	12 Missing and 5 partials ⚠️

❌ Your patch check has failed because the patch coverage (58.53%) is below the target coverage (95.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #12638      +/-   ##
==========================================
- Coverage   91.50%   91.46%   -0.05%     
==========================================
  Files         480      480              
  Lines       26464    26499      +35     
==========================================
+ Hits        24217    24238      +21     
- Misses       1778     1788      +10     
- Partials      469      473       +4     

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[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.

[milas]

RE: stale label - Happy to make any changes / rebase on main based on review if of interest to maintainers. Note that I'm not sure what's up with codecov, as there are unit test cases included. Otherwise, will let stalebot close.

[atoulme]

It's unclear if we would like to adopt this change. Please take a look at the checks CI failure - this is generating a path that is absolute and therefore no longer portable across machines. When would this approach make sense?

You also need to add a changelog entry for this PR. make chlog-new to generate the yaml template.

[milas]

Thanks for the reply!

this is generating a path that is absolute and therefore no longer portable across machines

Correct. I agree that behavior is not ideal, but fwiw it's the status quo:

opentelemetry-collector/cmd/builder/internal/builder/config.go

Lines 246 to 249 in e367eb1

	// Check if path is empty, otherwise filepath.Abs replaces it with current path ".".
	if mod.Path != "" {
	var err error
	mod.Path, err = filepath.Abs(mod.Path)

Today, if you do:

providers:
  - gomod: example.com/module v1.0.0
    path: ./mymodule

The resulting go.mod produced by ocb will have an absolute/non-portable path in the generated replace directive.

However, if you do:

replaces:
  - example.com/other => ./myvendor

The resulting go.mod produced by ocb will NOT have an absolute path for that replace directive.

In practice, this will break things:

/home/milas/mycollector/
  mymodule/
    go.mod
  myvendor/
    go.mod
  builder.yaml

When you run ocb, you'll end up with /home/milas/mycollector/dist/go.mod:

replace example.com/module v1.0.0 => /home/milas/mycollector/mymodule
replace example.com/other => ./myvendor

However, the correct relative path would be ../myvendor here, so it does not work as expected currently IMO, even non-portably.

Arguably, OCB could instead try to generate relative paths for the "dist" path based on the builder.yaml path: I did not attempt that for this since the module/component replacement was already using absolute/non-portable paths for the local replacement use case.

As a workaround, if you know the dist path will be a child, you can manually make the paths ../ instead of ./, though this inconsistent with the behavior of other paths.

In particular, that breaks my CI build flow (in a Docker container):

• Run DIST_OUTPUT_PATH=/dist ocb --config builder.yaml /src/builder-config.yaml --skip-compilation (scaffold but don't build)
• From /dist, run go build

Currently, I end up with a go.mod where my components have replace ... => /src/mymodule (works) but the generic "replace" has replace ... => ./myvendor (does not work).

---

You also need to add a changelog entry for this PR. make chlog-new to generate the yaml template.

ACK re: this + unit tests, will hold off for the moment until it's agreed that this makes sense in its current form -- I realize it's a pretty niche use case 😉

[github-actions]

This PR was marked stale due to lack of activity. It will be closed in 14 days.